1. Field of the Invention
The present invention relates to a method and apparatus for dressing hot rolled strip coils, especially coilbox coils. In hot wide strip mills or roll trains having a roughing train (consisting of one or more roughing stands), a following intermediate roller conveyer, and a subsequent finishing train, the slabs or blooms, which are heated in furnaces to the desired rolling temperature, and which can have, for example, a length of 9 m or more and a thickness of 100 to 170 mm or more, are first rolled in the roll stands of the roughing train into a rough strip having a thickness of 16 to 25 mm, or even up to 50 mm or more, and a width of for example 180 to 750 mm or more. This rough strip is then fed via the intermediate roller conveyer to the finishing train, in which it passes continuously, in succession, through several roll stands; in doing so, according to need, the rough strip is rolled out into a hot wide strip having a 1 to 12.5 mm thickness and, in conformity to the width of the roll stands, a width of about 550 to 2000 mm or even more. Depending upon the thickness and width of the hot strip, and the size of the initial blooms, the hot-rolled wide strip has a length of 750 to 1500 m or more. This long hot strip, which leaves the finishing train at temperatures above 800.degree. C., is therefore subsequently wound up by a reel into a coil and then cooled down on a cooling and delivery roller conveyer.
2. Description of the Prior Art
If the coils are not supplied directly as hot-rolled wide strip coils, as the product of the hot wide strip train, to subsequent users, for example cold-rolling mills, further handling, called dressing, takes place in a hot-strip dressing unit. By way of example, the wide strip, in a longitudinal dividing unit, is again unwound from the coil, trued, trimmed at the edges, and divided longitudinally into a medium strip or a narrow strip which is wound up again into coils. Alternatively, in transverse dividing units, the hot wide strip is unwound from the coil, trued, trimmed, and cut off into plates which are taken off in packs. Truing machines are used for the truing, for example roller truing machines, which have, for example, 11 to 17 rollers for heavy plates, medium plates, and thin plates, that is, according to plate thickness. For the trimming and division of the wide strip, shears or flame cutting units are used, depending upon the thickness. The unwinding of the coils, which precedes the above-mentioned further handling of the hot wide strip, takes place in a so-called uncoiling unit in which first in a coil-opening station the beginning of the strip of the hot-strip coil is bent open by means of a coil opener. Thereupon, the coil is received by an unwinding reel which is provided with a driven drive apparatus which pushes the beginning of the strip out of the reel and feeds it to a truing apparatus. These known uncoiling units can uncoil coils with the usual sheet or plate thickness of from about 1 or 1.5 to 13 or 16 mm, and singly even up to a maximum of 25 mm. Hot wide strips having greater thicknesses are not usual, and the known uncoiling apparatus are also not in a position to unwind cold coils having a greater plate thickness.
For technical reasons in rolling, in hot wide strip trains a so-called coilbox, into which the rough strip coming from the roughing stands is introduced, and in which it is wound into a coil, is frequently arranged between the roughing train and the finishing train. The coilbox, which is provided with appropriate drive systems, unwinds the coil again and feeds it to the finishing train. In the case of brief interruptions of operation, the coil can remain in the coilbox up to at most about 15 minutes. If the interruption lasts longer, too great a temperature loss occurs in the coiled rough strip, so that due to the fully continuous progress of operation of the hot wide strip train, the coil can no longer be handled further in the finishing train. These coils of cooled or cold rough strip, which can no longer be processed on the hot wide strip train, will hereinafter be called coilbox coils.
In heavy machine construction, for example, plates are required which, with a thickness in the range for example of 25 to 50 mm, lie far above the plate thickness of hot wide strip which is rolled on hot wide strip trains in general in thicknesses of 1 to 16 mm, and singly up to 25 mm. These thick plates having a thickness of 25 mm or more are rolled as a rule on four-high trains. Moreover, plates of this thickness, which however possess only a limited utility, occur as what is called roughing stand plate in hot wide strip trains without a coilbox if, in the case of the above-mentioned operating interruptions in the finishing train, the rough strip coming from the roughing stands of the roughing train cools so much that it can no longer be processed further on the finishing train, and if then this rough strip is cut off to so-called roughing stand plates. The only practical and possibly useful utilization of the coilbox coils would therefore be to uncoil them, true them, and cut them off into roughing stand plates of the desired size. The truing and division would be quite possible with the aid of roller truing machines and flame cutter units of the above-mentioned known style of construction for the dressing of hot strip coils. However, as already stated above, the known uncoiling units can uncoil only hot strip coils having the usual plate thickness of up to 13 mm, and at most up to 25 mm, and is not capable of processing coils with greater strip thicknesses. Uncoiling units which would render it possible to uncoil coilbox coils having a strip thickness of 25 to 50 mm do not exist, because such units in the traditional style of construction of the known uncoiling equipment would be so enormously expensive that such high and extensive investment would be completely uneconomical for the relatively low output of coilbox coils. Therefore, the coilbox coils occurring in hot wide strip trains are scrapped.
An object of the present invention therefore is to provide a method and an apparatus for dressing hot strip coils, especially coilbox coils, which render it possible to uncoil and true coilbox coils, but likewise also other hot strip coils, with technically simple and relatively cheap means, at such favorable cost that the material which previously was of only scrap value can be exploited as usable and salable roughing stand plate.